1. Field of the Invention
The present invention relates to a transport vehicle system such as an overhead travelling vehicle system and an unattended transport vehicle system and a transport method.
2. Description of the Related Art
There is known a transport vehicle system that includes at least one circulating route, a plurality of transport vehicles that travel in one direction along the circulating route, a transfer point placed along the circulating route where an article is transferred between the plurality of transport vehicles, and a transport vehicle controller that controls the travel of the plurality of transport vehicles. In addition, it is known that priority is assigned to a transport command and the transport command is executed from a higher priority, as disclosed in (JP2002-189520A). Transporting the article starts with picking up from the transfer point and ends with dropping off at the transfer point, so that priority of the transport command also means priority of pick-up from the transfer point. It is also known that pick-up is carried out in order from the transfer point on the downstream side when pick-ups are requested from a plurality of transfer points within the same circulating route, as disclosed in (JP5309814B).
However, there has not been a technology established which enables a balance in control focusing on priority and control focusing on the transfer point on the downstream side. If priority is focused on, the transport vehicle stops at the transfer point on the upstream side, resulting in an issue being created where the subsequent transport vehicles are prevented from picking up articles at the transfer points on the downstream side. Additionally, if priority is placed on pick-up on the downstream side, it creates an issue where the transport command with higher priority cannot be executed straight away.